On Thu, Apr 7, 2022 at 8:59 PM Andres Freund <and...@anarazel.de> wrote:
> > <para> > Cumulative statistics are collected in shared memory. Every > <productname>PostgreSQL</productname> process collects statistics > locally > then updates the shared data at appropriate intervals. When a server, > including a physical replica, shuts down cleanly, a permanent copy of > the > statistics data is stored in the <filename>pg_stat</filename> > subdirectory, > so that statistics can be retained across server restarts. In contrast, > when starting from an unclean shutdown (e.g., after an immediate > shutdown, > a server crash, starting from a base backup, and point-in-time > recovery), > all statistics counters are reset. > </para> > I like this. My comment regarding using "i.e.," here stands though. > > <para> > The cumulative statistics system is active during recovery. All scans, > reads, blocks, index usage, etc., will be recorded normally on the > standby. However, WAL replay will not increment relation and database > specific counters. I.e. replay will not increment pg_stat_all_tables > columns (like n_tup_ins), nor will reads or writes performed by the > startup process be tracked in the pg_statio views, nor will associated > pg_stat_database columns be incremented. > </para> > > I like this too. The second part with three nors is a bit rough. Maybe: ... specific counters. In particular, replay will not increment pg_stat_database or pg_stat_all_tables columns, and the startup process will not report reads and writes for the pg_statio views. It would helpful to give at least one specific example of what is being recorded normally, especially since we give three of what is not. David J.
